This project is a continuation of an ongoing investigation into the pathobiology of and factors associated with the vertical transmission of the Simian/Human Immunodeficiency Virus (SIV/HIV). In studies at TRPRC utilizing simian immunodeficiency virus (SIV)-infected pregnant macaques, chorioamnionitis (CA) and/or increased inflammatory infiltrates within placental tissues was associated with increased SIV antigen within placental tissues, early fetal demise, and SIV transmission to the infant. During year one (1998-99), this project will develop a primate model of chorioamnionitis by introducing 2 different species and 4 doses of bacteria into the choriodecidual space during pregnancy. During years 2-5, CA will be induced in a group of SIV-infected monkeys and the transmission outcome in this group will be compared to a group of monkeys infected with SIV alone to directly test the hypothesis that increases in inflammatory cell infiltrates within placental tissues increase the rate of transmission of immunodeficiency virus from mother to infant. Timed breeding programs were begun late in 1998 and pregnant monkeys are now being evaluated by ultrasound to begin this project. FUNDING Base Grant SIV Supplemental Funding PUBLICATIONS None